Urodynamic profile in myelopathies: A follow-up study.

AIMS
To study the significance of filling cystometry in assessment and management of neurogenic bladder in myelopathies and correlate neurological recovery and bladder management in the follow up.


STUDY DESIGN
Retrospective analysis of reports of filling cystometry in patients with traumatic and non-traumatic myelopathy.


SETTING
Neuro-rehabilitation unit of a tertiary care university hospital.


METHODS
The study was carried out between September 2005 and June 2006 and included all subjects with myelopathy who underwent filling cystometry. ASIA impairment scale was used to assess neurological status during admission as well as in the follow up. Bladder management was advised based on the cystometric findings. Neurological recovery and mode of bladder management were correlated during the follow up after a minimum of 6 months.


RESULTS
Fifty-two subjects (38 males, 14 females), mean age 33.26 +/- 14.66 years (10-80) underwent filling cystometry. Twenty patients had cervical, 24 had thoracic and 8 had lumbar myelopathy. Cystometric findings were overactive detrusor observed in 43 patients, (21 had detrusor sphincter dyssynergia (DSD), 22 without DSD) and areflexic/underactive detrusor in 9. Post-void residual (>15% of voided urine) was significant in 27 patients. Twenty-three patients (44%) reported for follow up (16 males, 7 females) after a mean duration of 9.04 +/- 2.44 months (6-15 months). Neurological recovery was seen in 61% cases, while 1 patient showed deterioration. Only 26% patients reported change in bladder management during follow up. Correlation between neurological recovery and bladder management was found to be insignificant (P > 0.05) using spearman correlation co-efficient.


CONCLUSIONS
Filling cystometry is valuable for assessment and management of neurogenic bladder after myelopathy. No significant relationship was observed between neurological recovery and neurogenic bladder management in the follow up in the present study.


Introduction
Spinal cord lesions oft en cause neurogenic bladder dysfunction [1] and interfere with activities of daily living, travel, sleep and personal relationship of the patients. The recovery of detrusor function and its control are of major importance to patients with myelopathy, family members, and health care providers. [2] Spinal control of micturition is located at S2 to S4 level of the spinal cord. This correlates to vertebral levels of T12 to L2 but it may vary slightly in each individual. [3] Signifi cant association exists between the level of a spinal cord lesion and its correlating bladder and sphincter behavior. Lesions above the spinal micturition center may lead to overactive detrusor and detrusor-sphincter dyssynergia (DSD), inducing refl ex micturition with increased detrusor leak point pressures, causing incontinence and consequent renal damage if untreated. [4] Neurological tests, such as perianal pinprick sensation and the bulbocavernous refl ex are moderately sensitive indicators of the return of bladder function aft er spinal cord injury. However, they are not predictive of the presence or absence of coexistent urodynamic abnormalities. [5] It has been observed that when the patient is fi rst seen in the peripheral health centers, usual practice is to manage bladder with indwelling catheter. It is imperative that urodynamic studies be performed at earliest and bladder is managed accordingly. It also helps in avoiding complications such as recurrent urinary tract infection and injury to the bladder, ureter and kidney.
This retrospective study was done to evaluate the signifi cance of fi lling cystometry in assessment and management of neurogenic bladder in patients with myelopathy during initial admission and to observe in the follow up, whether neurological recovery is correlated with mode of bladder management/voluntary micturition.

Materials and Methods
This study included 52 patients of myelopathy (traumatic and nontraumatic), who were receiving inpatient care in the Neurological Rehabilitation, Neurology or Neurosurgery unit. Patients younger than 7 years and with cognitive defi cits were excluded from the study.
Filling cystometry was performed over a period of 9 months (September 2005 to June 2006) using multichannel pressure recording technology with Phoenix MK (Allbyn Medical, Scotland, UK) equipment. No patient had urinary tract infection or pyrexia at the time of study. Patients were advised bowel program on previous day and enema for bowel evacuation in the morning on the day of procedure. Study was performed using International Continence Society guidelines and urodynamicist was present at the time of procedure. Filling cystometry was performed with the patients lying in supine position on the urodynamic table. Prior to commencing the urodynamic study, bladder was evacuated voluntarily by the patient, and then post-void residual was measured by catheterization. Bladder fi lling was done with infusion of normal saline at medium fi ll rate (10-100 ml/ minute). Two-lumen catheter was inserted in the urethra (one for infusion of normal saline and other for recording intravesical pressure). A rectal catheter was inserted for recording of intra-abdominal pressure. Recordings of bladder sensations, pressures (intravesical, abdominal and detrusor) and compliance were made during the procedure. (Defi nitions according to International Continence Society). [6] Patients were advised bladder management according to the observations made during the study with the goal to achieve a low-pressure reservoir and complete emptying. This management served as the baseline for subsequent urological evaluations. All patients were evaluated for neurological recovery as per American Spinal Injuries Association (ASIA) impairment scale before discharge. (ASIA impairment scale has 5 grades from A to E with A = Complete: No motor or sensory function is preserved in the sacral segments S4-S5, B = Incomplete: Sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5, C = Incomplete: Motor function is preserved below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3, D = Incomplete: Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more and E = Normal: Motor and sensory function are normal).
Follow up assessment was done, minimum six months after the discharge, which included assessment of bladder management and re-evaluation of neurological recovery as per ASIA impairment scale. All patients were advised ultra-sound (US) abdominal scan, complete routine and microscopic urine examination, urine culture and sensitivity. Filling cystometry was not repeated in any case in the follow up.
Defi nitions of terminology used in urodynamics: 1. Filling cystometry is the method by which the pressure/volume relationship of the bladder is measured during bladder fi lling 2. Detrusor pressure is that component of intravesical pressure that is created by forces in the bladder wall (passive and active). It is estimated by subtracting abdominal pressure from intravesical pressure 3. Detrusor overactivity is a urodynamic observation characterized by involuntary detrusor contractions during the fi lling phase which may be spontaneous or provoked 4. Bladder compliance is calculated by dividing the volume change by the change in detrusor pressure during that change in bladder volume. It is expressed in ml/cm H 2 O 5. Cystometric capacity is the bladder volume at the end of the fi lling cystometrogram, when "permission to void" is usually given
Patients were advised bladder management according to urodynamic findings, which are summarized in Table 4. Mode of bladder management initially and during the follow up along with neurological status is summarized in Tables 5 and 6.
Out of those 23 patients who reported for follow up, 14 (61%) showed neurological improvement [ Table 6]. One patient (4%) of lumbar myelopathy had deterioration    (from ASIA D to ASIA C during follow up).
No significant correlation was found (p = 0.926) between neurological status and method of the bladder management (Using spearman correlation coeffi cient) as 50% of cervical myelopathy patients who showed improvement in neurological status were still following same bladder management method at follow up. Nearly 57% of thoracic myelopathy cases, which showed neurological improvement did not report any change in their mode of bladder management at follow up. One patient with lumbar myelopathy showed improvement and one patient with spinal tumor had deterioration in neurological status according to ASIA impairment scale at follow up but it is signifi cant to note that neither patient reported change in their method of bladder management.

Discussion
Historically, before urodynamic study with the coupling of cystometry and sphincter electromyography allowed the clinician to accurately diagnose DSD, mode of bladder management was chosen empirically, without reliance on objective testing.
The fl aw with empirical therapy based on achieving a balanced bladder is that elevated intravesical pressure, responsible for the majority of urologic sequelae in patients with neurogenic lower urinary tract dysfunction, may be clinically silent. Indeed, low residual urine volume does not insure against severe urologic complications. [5] The International Continence Society has published guidelines regarding fi lling cystometry, pressure-fl ow studies, and urethral pressure measurement in order to standardize the reporting of urodynamic results and technique. [7,8] The urodynamic manifestation of the neurogenic bladder dysfunction could be divided into three groups according to the category of the detrusor refl ex activity: (a) overactive detrusor without dyssynergia, (b) overactive detrusor with dyssynergia and (c) detrusor arefl exia. [9] In our study, 82.7% patients showed overactive detrusor during filling cystometry with nearly half of them having had concurrent DSD. Remaining patients showed areflexic/hypoactive detrusor. The high number of overactive detrusor with or without DSD in our study was due to the fact that 85% of our patients had cervical or thoracic myelopathy, hence had supra sacral lesion in the spinal cord. Three cases of lumbar myelopathy showed overactive detrusor in urodynamics. One of these had myelopathy and two had cauda equina lesions. Patients with lesions of the cauda equina, far below the conus medullaris support the view that an overactive bladder may also be found in absence of an upper motor neuron lesion. It may be a consequence of decentralization of the parasympathetic ganglia situated within the bladder wall [10,11] or irritation of the lower sacral roots (as a ''positive symptom'' of the nerve lesion).
The treatment methods of the neurogenic bladder dysfunction include pharmacotherapy, training of the pelvic floor muscles, retention type catheter, sacral root electrical stimulation, [12,13] selective sacral root rhizotomy, pudendal nerve stimulation, [14] section of the external urethral sphincter [15] and insertion of the artifi cial urethral sphincter, [16] depending upon the type of bladder according to urodynamic evaluation. The goal is to maintain a low pressure, normal compliance of the bladder, eliminate the threat to the renal function and improve the quality of life.
Majority of patients in the study had incomplete cord lesion. This is understandable as nearly 70% patients had non-traumatic myelopathy in the study. Non-traumatic myelopathies more commonly present as incomplete cord lesions with thoracic and lumbar region as the more common site of lesion.
During follow up, 25% patients with cervical myelopathy were doing voluntary micturition with no backpressure changes. Three patients with cervical myelopathy, who were doing timed voiding (TV) along with anticholinergic medication, were doing same even in the follow up. Two out of 9 patients of thoracic myelopathy started doing voluntary micturition by the time of follow up and 5 patients were following same method. Out of 6 patients with lumbar myelopathy, no change was noted in the mode of bladder management at follow up. Four patients who were doing TV were still following same method in the follow up. No patient in the study, who Fourteen patients (61%) showed neurological improvement according to ASIA impairment scale during follow up. Six out of these 14 patients had cervical myelopathy and only 3 out of these 6 cases showed change in their method of bladder management. Similar trend was noted in patients with thoracic myelopathy as out of 7 cases that showed neurological improvement, only 3 showed change in the method of bladder management. One case of lumbar myelopathy had neurological recovery and other had deterioration. Interestingly, neither cases show any change in the method of bladder management.

Limitations of the study:
This study had a few limitations. Patients had diverse etiology, level and completeness of myelopathies. Sample size is small and further, follow up was limited to 44% patients. Urodynamic study was not repeated in the follow up because of fi nancial constraint and reluctance of the patients to stay in the hospital for the same.

Conclusions
Spinal cord lesions are well known to cause neurogenic bladder dysfunction. Management of which, is of major importance not only for the patient but also for the caregivers. A signifi cant association exists between the level of spinal cord lesion and the character of recovery of detrusor and sphincter function. Performing timely urodynamic procedure can best elucidate this association.
Filling cystometry is valuable in the diagnosis, classification, management and prognosis of the neurogenic bladder dysfunction. Proper bladder management according to the observations made during fi lling cystometry study helps in avoiding secondary complications in the urinary tract.
No significant relationship was observed between neurological recovery and mode of neurogenic bladder management in the follow up in this study.